Merge Sort

//Jiban
//192-15-13117
#include<stdlib.h>
void merge(int arr[], int l, int m, int r)
{
int i, j, k;
int n1 = m - l + 1;
int n2 = r - m;
int Lt[n1], Rt[n2];
for (i = 0; i < n1; i++)
{
Lt[i] = arr[l + i];
}
for (j = 0; j < n2; j++)
{
Rt[j] = arr[m + 1+ j];
}
i = 0;
j = 0;
k = l;
while (i < n1 && j < n2)
{
if (Lt[i] <= Rt[j])
{
arr[k] = Lt[i];
i++;
}
else
{
arr[k] = Rt[j];
j++;
}
k++;
}
while (i < n1)
{
arr[k] = Lt[i];
i++;
k++;
}
while (j < n2)
{
arr[k] = Rt[j];
j++;
k++;
}
}

void mergeSort(int arr[], int l, int r)
{
if (l < r)
{
int m = l+(r-l)/2;
mergeSort(arr, l, m);
mergeSort(arr, m+1, r);
merge(arr, l, m, r);
}
}
void printArray(int A[], int size)
{
int i;
for (i=0; i < size; i++)
{
printf("%d ", A[i]);
}
printf("\n");
}
int main()
{
    int sum=0,remainder;
    int digitSum=0;
int arr[1000], arr_size;
printf("Enter Number of Elements in Array: ");
scanf("%d", &arr_size);
printf("Enter Elements of Array: ");
for(int i = 0; i < arr_size; i++)
{
scanf("%d", &arr[i]);
}
mergeSort(arr, 0, arr_size - 1);
printf("\nSorted Array is: ");
printArray(arr, arr_size);
for(int i=0; i<arr_size; i++)
{
   sum=sum+arr[i];
}
printf("Sum = %d\n", sum);
while(sum>0)
{
remainder=sum%10;
digitSum=digitSum+remainder;
sum=sum/10;
}
printf("Digit(s) Sum: %d\n",digitSum);
return 0;
}